Is a covariant virtual tachyon viable?
The paper investigates if purely virtual tachyons, within the fakeon framework, can be consistent with quantum field theory. It shows that while free tachyon propagators have specific behaviors, interactions with stable Standard Model fields lead to Lorentz invariance violations and matter-dependent accelerations that violate the weak equivalence principle. The analysis concludes that a covariant QFT of interacting virtual tachyons is not viable.